The present invention relates generally to a lock construction and particularly to a lock for securing trailers against unauthorized attachment to a trailer hitch of a towing vehicle. Conventionally, trailers are connected to a trailer hitch secured to a towing vehicle for towing the trailer behind the vehicle. The trailers are constructed with a trailer hitch socket that extends from the trailer and is attached to a connecting member, such as a ball, mounted on a towing bar secured to the towing vehicle. The connecting member is normally held in the trailer hitch socket by retractable devices that are operated by a clasp or a lever. Once the socket is fitted over the connecting member, the retractable devices engage the lower half of the member and the lever secures the retractable devices over the member. Once engaged, the retractable devices prevent the separation of the trailer from the towing vehicle until the retractable devices are released by the lever. When the trailer is not being towed, it is often disengaged from the vehicle, leaving the trailer highly susceptible to theft due to the ease of attaching the trailer socket to a trailer hitch of an unauthorized vehicle.
Several devices have been developed to prevent trailer theft by preventing connection of the trailer hitch socket to the trailer hitch of an unauthorized towing vehicle. U.S. Pat. No. 5,332,251 to Farquhar discloses a trailer hitch lock assembly comprising an upper bolt plate with a bolt that engages a lower shield plate. A separate padlock is used to engage a hole in the bolt to secure the bolt plate and the shield plate togther. The use of the separate padlock for securing the plates together makes the lock more difficult to operate due to the additional attachment of parts. Additionally the padlock is exposed, allowing access for tampering with the locking mechanism.
U.S. Pat. Nos. 4,032,171 to Allen et al. and U.S. Pat. No. 5,873,271 to Smith both disclose trailer hitch locks that are adaptable for use with a trailer having a ball shaped connecting member. The Allen trailer hitch lock discloses a separate padlock for securing the locking assembly. As in the lock disclosed in Farquhar, the Allen lock construction leaves the padlock open to tampering. Smith discloses a lock having upper and lower jaws such that the upper jaw is moveable vertically between the locked and unlocked positions. The vertical construction makes the lock difficult to operate wherein the upper jaw must be manually lifted and adjusted to accommodate different sizes of trailer sockets.
Accordingly, there is a need for a lock that is adaptable to different types and sizes of the socket on the trailer and provides greater ease in operation while maintaining a high level of security.
The present invention is directed to a lock construction for securing to a trailer socket and thereby preventing attachment of the trailer socket to a connecting member of an unauthorized towing vehicle. The lock construction comprises a base with a first upstanding member extending from the base and adapted to engage the trailer socket of the trailer. A second upstanding member is disposed on the base in spaced relation to the first upstanding member. A shaft like member is positioned in the housing and is slidable toward the upstanding member from an unlocked position where the shaft is spaced away from the upstanding member to a locked position wherein the shaft engages the trailer socket once it is attached to the upstanding member. A locking mechanism is operatively connected to the shaft for movemenet between a first position to release the shaft for slidable movement and a second position to prevent the shaft from slidable movement. The lock additionally includes a ratchet member and ratchet surface, allowing slidable movement of the shaft to different locked locations.